The formation of A2 oligomers (ADDLs) and their subsequent binding and toxicity to neurons are seen as the initial events in Alzheimer<s disease (AD) pathogenesis. Many of the signaling pathways through which ADDLs act to cause synaptic and cellular degeneration have been identified, however little is known about the signal- ing cascades responsible for protecting neurons against ADDLs. Insulin signaling has been identified by our lab as an anti-ADDL protective pathway, preventing ADDL binding and toxicity to hippocampal neurons. This protective role is further supported by in vivo and in vitro evidence that indicates insulin dysfunction may be a predisposing factor for AD. Although insulin signaling appears to be important in regulating the susceptibility of neurons to the synaptotoxic attack of ADDLs, the mechanism is unknown. The first aim of this proposal investi- gates the protective mechanism by which insulin prevents ADDL binding with the hypothesis that insulin treat- ment causes the removal of surface proteins to which ADDLs attach. Intracellular uptake and extracellular re- lease of proteins will be distinguished using reversible surface biotinylation with co-immunoprecipitation. Using pharmacological inhibitors, I will determine which insulin signaling cascades are responsible for the anti-ADDL effects of insulin. These cascades will be validated for their activation kinetics using phospho-specific antibod- ies coupled with fluorescence microscopy, My second aim evaluates the ability of naturally-derived insulin mi- metics to act as anti-ADDL therapeutics and evaluate their mode of action in neural cells. As a result of this project, we will better understand insulin signaling in the CNS. More importantly, we will likely have identified new lead compounds for AD therapeutics. PUBLIC HEALTH RELEVANCE: The goal of this project is to understand how brain cells respond to insulin. The response to insulin is important for normal cell functioning, and it seems to be disrupted in Alzheimer<s disease. Findings from these studies will benefit our understanding of normal brain functioning and the role of insulin in protecting the brain against Alzheimer<s disease.